When you close the page, the Window tries to dispose and this causes an exception that you can see in the Output > ASP.NET Core Server window. The exception does not show up in the browser, but shows up in the logs.


WARN  2019-12-17 09:26:16,300 Unhandled exception rendering component: Cannot process pending renders after the renderer has been disposed.
Object name: 'Renderer'.
System.ObjectDisposedException: Cannot process pending renders after the renderer has been disposed.
Object name: 'Renderer'.
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(Int32 componentId, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
   at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContextDispatcher.InvokeAsync(Action workItem)
   at Microsoft.AspNetCore.Components.ComponentBase.InvokeAsync(Action workItem)
   at Telerik.Blazor.Components.TelerikWindowBase.Refresh()
   at Telerik.Blazor.Components.TelerikWindowBase.Dispose()
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.Dispose()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.Dispose(Boolean disposing)